Silence from your teenage son is a trying dynamic. The silence is deafening and fills you and the house. It is unsettling and likely causes agitation within you. He is exacting his message towards you without a word. He is angry and wants you to know it. The longer this dynamic continues the harder it is to correct. He is approaching adulthood and unless this behavior is eradicated from him, he will continue the behavior into the work place and significant relationships.
Have a Voice
Voicing your concerns to your son can begin to break the ice. How you approach him is the difference between giving into him and taking control of the situation. Approach him with confidence, without expecting a response, and address the elephant in the room. Say something like "I know you are upset with me and this is your way of punishing me. I don't accept this behavior. I am ready to talk with you when you are." Stating the obvious deflates his position and puts the power back in your hands. Walk away once you finish your statement. This diffuses a power struggle in the moment, allows him to think about what you said and gives him time to get himself together. This approach also changes the dynamic from silent treatment to pouting. It is advisable to take his cell phone and other electronics until he talks with you appropriately.
Move on with your day. Go about your day as planned. The more you are unaffected by his behavior the less power you are giving to him. He needs to get the message he is only hurting himself by this chosen behavior. He wants to control you, to make you feel guilty and to manipulate you. By moving on with your day, you're removing any satisfaction he gets from seeing you miserable. Laugh, sing or talk with your friends to communicate to him he isn't ruining your day. He will likely be irritated by this and that irritation will motivate him to end his silence and talk with you.
Talk it Through
Talk with him when he comes to you. This isn't the time to feign unavailability. You want to reinforce positive behavior. Start the conversation by praising his choice to talk and that you are ready to listen. Watch your tone of voice and body language because he is likely feeling awkward and looking for a reason to retreat again. Don't give him a reason. Encourage him to keep advancing and to sit and talk through what lead to his silent treatment. Give him eye contact, really listen and converse with him. Point out the positive choices he did make through this situation, no matter how small.
Teaching your son is a parent's responsibility. He likely choose the silent treatment because that is all he knows to do when he is angry with an authority figure. Use this situation as a teachable moment. This should only start once the above step is complete. Avoid mixing these two steps. Waiting until the problem issue has been resolved allows him to shift his focus onto his behavior. Talk through why he made that choice and create a plan together of healthy choices he can make when he is upset. Consider the following ideas: having a keyword that signals he is upset, ask for a time out with a definitive amount of time after which he comes out and talks with you, or write a letter and brings it to you that will lead to a discussion. This should be a joint process with him doing most of the work. Have him write it down as he comes up with ideas and have him put it somewhere he can access whenever he needs it.